Flight

Launch from the Baikonur Cosmodrome; landing
135 km north of Arkalyk. The launch was delayed three days of unspecified
cause.

Soyuz 28 marked the first Interkosmos mission
with a foreign cosmonaut on board. The Czechoslovakian Vladimir
Remek became the first cosmonaut of his country. Aleksei
Gubarev and Vladimir
Remek, the first non-Soviet, non-American to travel to space,
were launched aboard
Soyuz 28 on March 02, 1978, after a three-day delay of
unspecified cause.

Following a one day solo flight
Soyuz 28 docked with the
Salyut 6 space station on March 03, 1978. The visiting
cosmonauts were greeted by the
first resident
crew Georgi
Grechko and Yuri
Romanenko who had arrived on
Soyuz 26 in December 1977. Aleksei
Gubarev and Georgi
Grechko had previously flown together on
Soyuz 17 to the
Salyut 4 space station in 1975. The docking with
Salyut 6 took place on March 03, 1978 at 17:09
UTC, with Aleksei
Gubarev docking at the unoccupied aft aperture - the forward
docking port was already occupied by the Soyuz 27 craft. The visiting cosmonauts brought with them
letters, newspapers, and magazines for the resident crew.

Interkosmos
missions had mainly political purposes but also some scientific experiments
were performed, including one which monitored the growth of Chlorella seaweed
in zero gravity, another which used the on-board Splav furnace to melt glass,
lead, silver and copper chlorides, and an experiment called Oxymeter which
measured oxygen in human tissue. Vladimir
Remek's experiment program touched on life sciences,
materials processing, and upper atmosphere research.

The experiments
performed by both crews included:Khlorella-1 (Chlorella, or green
freshwater algae): A study of the effects of microgravity on the growth of
unicellular algae, which served as a model for fast-growing organisms. All the
samples were carried in soldered ampoules stored in four containers with a
nutrient medium. The aim of the experiment was to learn more about the future
use of algae in air and water recycling systems aboard spacecraft. It was
determined that microgravity does not affect the speed at which algae
populations grow.Morova-Splav and Morava-Kristall (Morova is a river
in Czechoslovakia; "splav" means "alloy"): A series of materials-processing
experiments with the aim of obtaining materials in space that cannot be
obtained on Earth. The experiments, prepared jointly by the Solid Body Physics
Institute of the Czechoslovakian Academy of Sciences and the Institute of Space
Research in Moscow, studied the solidification of melted crystalline and glassy
materials and the growth of crystals from the gas phase. Kislorod
(Oxygen): An experiment to study any changes in the supply of oxygen to various
parts of the human tissue during flight and to see how human tissue uses oxygen
in microgravity. The experiment was carried out with a portable Czech-built
device called Oximeter, consisting of an array of special sensors.
Oprosnik (Questionnaire): Twice during the flight the cosmonauts
filled out a questionnaire on their medical and psychological condition. The
questions related to such things as the cosmonauts' food and water consumption,
sleep patterns, eyesight, sense of smell, ability to hear and aesthetic
requirements, which they had to assess on a scale of five. Jointly developed by
Soviet, Czech and Polish specialists, this experiment was designed to help
determine how people adapt to the unusual conditions of spaceflight, and to
further improve living and working conditions in confined spaces.
Teploobmen-2 (Heat Exchange 2): An experiment designed to study the
cooling effects of the space station's atmosphere. The cooling of objects that
produce heat significantly changes in zero-g as one of the main elements of
heat exchange - namely heat emission through natural convection - is missing.
Ekstinktsia (Extinction): The crew visually observed how the
brightness of stars changed as they disappeared behind the horizon. Earlier
Soviet and American crews had noticed that stars begin fading when they are
still about 100 km from the horizon. At the time, no satisfactory explanation
had been found for this phenomenon. The cosmonauts' task was to determine
changes in the magnitude, color and scintillation of stars as they approached
the horizon, which would help develop a photometer to carry out similar
observations on future missions. Such a photometer was being developed at the
time by the Astronomical Institute of the Czechoslovak Academy of Sciences in
Ondrejov.

On March 10, 1978, the
Soyuz 28 crew prepared for their return to Earth,
packing experiments and testing systems. They returned silver chloride capsules
and copper and lead chloride samples from the
Salyut 6 materials experiments. The cosmonauts
undocked from the station and landed 135 km north of Arkalyk later that day.

The
Soyuz spacecraft is composed of three elements
attached end-to-end - the Orbital Module, the Descent Module and the
Instrumentation/Propulsion Module. The crew occupied the central element, the
Descent Module. The other two modules are jettisoned prior to re-entry. They
burn up in the atmosphere, so only the Descent Module returned to
Earth.Having shed two-thirds of its mass, the
Soyuz reached Entry Interface - a point 400,000 feet
(121.9 kilometers) above the Earth, where friction due to the thickening
atmosphere began to heat its outer surfaces. With only 23 minutes left before
it lands on the grassy plains of central Asia, attention in the module turned
to slowing its rate of descent.Eight minutes later, the spacecraft was
streaking through the sky at a rate of 755 feet (230 meters) per second. Before
it touched down, its speed slowed to only 5 feet (1.5 meter) per second, and it
lands at an even lower speed than that. Several onboard features ensure that
the vehicle and crew land safely and in relative comfort.Four parachutes,
deployed 15 minutes before landing, dramatically slowed the vehicle's rate of
descent. Two pilot parachutes were the first to be released, and a drogue chute
attached to the second one followed immediately after. The drogue, measuring 24
square meters (258 square feet) in area, slowed the rate of descent from 755
feet (230 meters) per second to 262 feet (80 meters) per second.The main
parachute was the last to emerge. It is the largest chute, with a surface area
of 10,764 square feet (1,000 square meters). Its harnesses shifted the
vehicle's attitude to a 30-degree angle relative to the ground, dissipating
heat, and then shifted it again to a straight vertical descent prior to
landing.The main chute slowed the
Soyuz to a descent rate of only 24 feet (7.3 meters)
per second, which is still too fast for a comfortable landing. One second
before touchdown, two sets of three small engines on the bottom of the vehicle
fired, slowing the vehicle to soften the landing.